Tangentially finned heat exchange tubes



Dec. 11, 1951 HUET TANGENTIALLY FINNED HEAT EXCHANGE TUBES 2 SHEETS-SHEET 1 Filed May 16, 1947 INVENTOR. ,4/1dre 644 2 I ATTORNEY Dec. 11, 1951 A. HUET TANGENTIALLY FINNED HEAT EXCHANGE TUBES 2 SHEETSSI-[EET 2 Filed May 16, 1947 INVENTOR. Andre floe/ A TTORNEY Patented Dec. 11, 1951 TANGENTIALLY rmuno HEAT EXCHANGE rum-1s Andre Huet, Paris, France Application May 16, 1947, Serial No. 748,561 In France May 24, 1946 3 Claims. (01. 257262) The present invention relates to heat exchange members such as tubes having extended surface in the form of fins.

Heat exchange tubes provided with fins are well known but the present invention contemplates a novel arrangement of longitudinally extending fins on such tubes and the disposition of the latter in the gas passage in such manner as to increase the heat exchange between gases flowing over the surfaces of the tubes and fins and a fluid traversing the tubes.

The invention will be best understood upon consideration of the following detailed description of an illustrative embodiment thereof when read in conjunction with the accompanying drawings in which:

Figure 1 is a partial plan view of a heat exchanger such as an economizer having tubular elements provided with fins in accordance with the present invention;

Figure 2 is an elevational view of an economizer, partly in section, along the line 2--2 in Figure 1; and

Figure 3 is a transverse sectional view on an enlarged scale of a number of tubes provided with fins in accordance with the invention.

The economizer shown in Figs. 1 and 2 comprises a plurality of multi-loop heat exchange elements made up of parallel tubes l interconnected at their adjacent ends by return bends H with the extreme ends of the elements connected to the inlet and outlet headers l2 and i3 respectlvely. When employed as an economizer, such a heat exchanger is usually located in the outlet of the boiler in a gas passage l5 so that the heat of hot gases passing over the tubular elements is transmitted to water circulated through the tubular elements connected to the inlet and outlet headers l2. l3.

As is best seen in Fig. 3, each tube It is provided with two fiat longitudinally extending fins and 2-! welded at 180 with respect to each other on the periphery of the tube and projecting in directions approximately tangential to the section of the tube. As shown in the drawings the tubes Ill are arranged at equal intervals in staggered relation in uniformly spaced parallel rows and disposed in such fashion in the gas passage that the fins 20, 2| are on the upstream and downstream faces of the tubes and slightly inclined with respect to the general direction of the heating gas current which follows the direction of the arrow A. This inclination could be dispensed with and the fins 20, 2| located parallel to thAe. direction of gas flow as indicated by arrow With the arrangement described above, the main fluid stream flowing in the direction of arrow A is split up by the upstream fin 20 so that the left hand current comes into contact with the tube III as indicated by the arrow B and wipes against about of is surface; at the moment, when conforming to conventional aero-dynamic theories, the stream should begin to fiow around the back face 22 of tube It) and create a void with eddy currents, it has reached the base of the fin 2| which it sweeps over on the left hand face in the direction of the arrow C. On the right hand face of the upstream fin 20 the fiuid current which follows the arrow D wipes against about 120 on the right hand face of the tube 10 and in following the arrow E curves against the back of the tube and is finally turned away by the right hand face of the downstream fin 2! so as to follow the arrow F.

It may be seenthat with this arrangement the entire surface of a tube It and its fins 20, 2| is scoured by the currents of hot gases and consequently an optimum heat exchange is assured.

From one row to another of tubes in the heat exchanger the fins can be disposed parallel in similar fashion or can be alternated so that upstream fins are first on the right, then the left,

etc. With the tubes spaced at like distances in each row and the fins in corresponding locations on the tubes, the upstream fin 20 on tubes of one row aline with the downstream fins 2| in a following row. The distal edges of the fins may be close together or actually in contact to form separate gas lanes. When the tube rows are staggered, the arrangement as shown in Figure 3 places the tubes in the intermediate rows 0pposite the distal ends of fins on tubes in the immediately following and preceding rows. This narrows the gas lanes at H and widens them at N. Thus, in the entire volume of heat exchange pass there are a number of sinuous passages made up of alternately narrowing parts H followed by widened parts N in continuous series through the bank. In passing through the narrow sections H the velocity of the stream increases and then upon expanding in the widened sections N the energy obtainable is converted from velocity to static pressure so that the streams completely fill the channel spaces between the tubes and the heating gas fiows in intimate contact with the tubes and their fins to assure the most efilcacious heat transmission between the gas and the fluid flowing through the interior of the tube It).

It is to be noted that there is practically no 3 aerodynamic shadow or eddy zone on the downstream side of the tubes where the cinders or slag can accumulate.

What is claimed is:

1. In a heat exchanger having a gas passage through which heating gases flow over a plurality of fluid circulating tubes disposed transversely of the gas stream in spaced relation in several parallel rows located in planes perpendicular to the direction of gas flow; a pair of heat transfer fins mounted at substantially diametrically spaced points on the tubes to extend longitudinally thereof and projecting approximately tangentially from the tube surfaces, the tubes in adjacent rows being staggered with respect to each other and being so disposed in the gas passage that fins on opposite sides of tubes in alternate rows have their distal ends alined and substantially in contact with each other so as to divide said passage into a number of sinuous gas lanes therebetween.

2. In a heat exchanger having a gas passage through which heating gases flow over a plurality of fiuid circulating tubes disposed transversely of the gas stream in spaced relation in several parallel rows located in planes perpendicular to the direction of gas flow; a pair of heat transfer fins mounted at substantially diametrically spaced points on the tubes to extend longitudinally thereof and projecting approximately tangentially from the tube surfaces, the tubes in adjacent rows being staggered with respect to each other and being so disposed in the gas passage that fins on opposite sides of tubes in alternate rows have their distal ends alined with each other so as to divide said passage into a number of sinuous gas lanes therebetween, the tubes being so oriented that the fins thereon project from their surfaces into the gas stream at angles slightly inclined with respect to planes parallel with the general direction of gas flow through said passage.

3. In a heat exchanger having a gas passage through which heating gases fiow over a plurality of fluid circulating tunes disposed transversely of the gas stream in spaced relation in several parallel rows located in planes perpendicular to the direction of gas flow; a pair of heat transfer fins mounted at substantially diametrically spaced points on the tubes to extend longitudinally thereof and projecting approximately tangentially from the tube surfaces, the tubes in adjacent rows being staggered with respect to each other and being so disposed in the gas passage that fins on opposite sides of tubes in alternate rows have their distal ends alined and substantially in contact with each other so as to divide said passage into a number of sinuous gas lanes therebetween, the tubes being so oriented that the fins thereon project from their surfaces into the gas stream at angles slightly inclined with respect to planes parallel with the general direction of gas fiow through said passage.

ANDRE HUET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 767,187 Wadham Aug. 9, 1904 1,757,621 De Lorenzi May 6, 1930 1,884,777 Lucke Oct. 25, 1932 2,167,333 Foss July 25, 1939 2,185,928 Simpson et al Jan. 2, 1940 2,277,921 McCullough et al. Mar. 31, 1942 2,444,908 Bailey et a1 July 13, 1948 

